jay gray joins us now from the courthouse in sanford, florida where the trial is now in its third week. jay? >> reporter: an important and busy day. the first day of presentation, full day of presentation from the defense and you're right. focused that now familiar 911 call but for the first time we heard from trayvon martin's father about what he said he heard on that recording. tracy martin was at the center of an intense and emotional day of testimony. >> best friend in life and to have him gone is tragic. >> reporter: trayvon martin's father said initially he wasn't sure who was screaming in the background of the 911 call the night his son was killed. >> didn't tell them no that wasn't trayvon, i kind of -- i think i pushed away from the be table and just kind of shook my head and said i can't tell. >> so your words were i can't tell. >> something to that effect but i any severe said no that wasn't my son's voice. >> reporter: george zimmerman told police it's his voice supreming for help. he's pleaded not guilty to second-degree murder in the case saying he acted in self-defense.